Infectivity of Chordodes nobilii larvae (Gordiida: Nematomorpha) / Infectividad de las larvas de Chordodes nobilii (Gordiida: Nematomorpha)

AbstractThe gordiids are freshwater representatives of the parasite phylum Nematomorpha that function as a link between aquatic and terrestrial ecosystems. In recent years, different ecotoxicologic studies have been made with the South-American gordiid species, Chordodes nobilii, that have demonstrated the capacity of this group to act as a bioindicator of contamination. Despite the Gordiida's ecologic relevance, further studies are still needed to elucidate different aspects of the biology of the class, and among those, the infective capacity, a parameter that can be evaluated by the infection index mean abundance (IIMA). A knowledge of the intrinsic variability in the infective capacity of C. nobilii would warrant priority in order to establish, the range of acceptable responses for normal or standard conditions in the laboratory, and, to compare the criteria among different assays. The objective of this study was to establish a baseline value for the infective capacity for C. nobilii larvae, under controlled laboratory conditions, by employing the IIMA as the evaluation parameter. To that end, we analyzed the infective capacity of C. nobilii larvae that had hatched from different strings of eggs laid in the laboratory by a total of 12 females. The C. nobilii adults were collected from streams within the Argentina Sauce Grande basin, between 2006 and 2009. Once in the laboratory, after mating, the females were placed in individual containers for oviposition. The egg strings obtained from each female were cut in 3 mm long segments; and when free larvae were observed, the segments (N= 90) were placed together with 30 Aedes aegypti larvae for evaluation of the gordiids' infective capacity. After 72 h, the mosquito larvae were observed by microscopy in order to quantify the C. nobilii larvae in body cavities. The IIMAs were calculated as the total number of C. nobilii larvae present divided by total number of A. aegypti larvae examined. For analysis of the IIMAs obtained, the data were grouped according to the female who made the original ovoposition. Our results enabled the corroboration of an ample range of responses in the infective capacity of this species, a characteristic that would normally be linked to the progenitors originating the hatch. Because this relationship prevents the establishment of a baseline for making comparisons among assays with gordiids, through the IIMA as a response parameter, we recommend expressing the IIMA values in each assay relative to their respective controls. These findings also provide evidence for the greater success in infections by certain members of the progeny over others. Finally, on the basis of the results obtained from this study, we stress the relevance of the use of the IIMA as a decisive aspect to be considered in different studies on the biology of Gordiida. Rev. Biol. Trop. 65 (1): 1-8. Epub 2017 March 01.

ResumenLos gordiidos son representantes dulceacuícolas del Phylum parásito Nematomorpha que actúan como un enlace entre ecosistemas acuáticos y terrestres. En años recientes, diferentes estudios ecotoxicológicos se han desarrollado con una especie sudamericana de gordiido, C. nobilii, que ha demostrado la capacidad de este grupo de actuar como bioindicador de contaminación. A pesar de su evidente importancia ecológica, aún se necesitan realizar estudios para dilucidar distintos aspectos de su biología, entre estos, la capacidad infectiva, un parámetro que puede evaluarse utilizando el Índice de Infección Abundancia Media (IIMA). El conocimiento de la variabilidad intrínseca en la capacidad infectiva de C. nobilii merece prioridad con el objeto de establecer el ámbito de respuesta aceptable para condiciones normales o estándar en el laboratorio, y que permita comparar los resultados entre distintos ensayos. El objetivo de este estudio es establecer la línea de base de la capacidad infectiva del gordiido C. nobilii en condiciones controladas de laboratorio, empleando el IIMA como parámetro de evaluación. Con este fin, se analizó la capacidad infectiva de larvas de C. nobilii que eclosionaron de diferentes cordones de huevos depositados por un total de 12 hembras, mantenidas en laboratorio. Los adultos de C. nobilii fueron recolectados de arroyos de la cuenca argentina Sauce Grande, entre 2006 y 2009. Una vez en el laboratorio, después de la cópula, las hembras se ubicaron en recipientes individuales a la espera de la oviposición. Los cordones de huevos obtenidos de cada hembra se cortaron en segmentos de 3 mm de longitud; y cuando las larvas libres fueron observadas al microscopio, los segmentos (N= 90) fueron ubicados junto con 30 larvas de Aedes aegypti para evaluar la capacidad infectiva del gordiido. Después de 72 h, las larvas del mosquito fueron observadas al microscopio para contabilizar las larvas de C. nobilii en las cavidades corporales. El IIMA fue calculado como el número total de larvas de C. nobilii presentes dividido entre el número total de larvas de A. aegypti examinadas. Para el análisis de los IIMAs obtenidos, los datos fueron agrupados de acuerdo a la hembra que hizo la oviposición. Nuestros resultados permiten corroborar un amplio rango de respuesta en la capacidad infectiva de esta especie, que estaría vinculada al origen de la camada. Debido a que no se pudo establecer una línea de base para realizar comparaciones entre estudios en los gordiidos utilizando el IIMA como parámetro de respuesta, se aconseja relativizar los valores de los IIMAs a sus respectivos controles. Estos resultados también pusieron en evidencia la ventaja en el éxito de infección de algunas progenies sobre las restantes. Finalmente, con base en los resultados obtenidos a partir de este estudio se plantea la importancia del uso del IIMA como punto final a considerar en distintos estudios sobre la biología de los gordiida.

Macelignan inhibits bee pathogenic fungi Ascophaera apis growth through HOG1 pathway

Ascosphaera apis is a bee pathogen that causes bee larvae infection disease, to which treatment is not yet well investigated. The aim of this study was to investigate antifungal susceptibility in vitro against A. apis and to identify a new antifungal agent for this pathogen through minimal inhibitory concentration (MIC) assay and western blot analysis. Macelignan had 1.56 and 3.125 μg/mL MIC against A. apis after 24 and 48 h, respectively, exhibiting the strongest growth inhibition against A. apis among the tested compounds (corosolic acid, dehydrocostus lactone, loganic acid, tracheloside, fangchinoline and emodin-8-O-β-D-glucopyranoside). Furthermore, macelignan showed a narrow-ranged spectrum against various fungal strains without any mammalian cell cytotoxicity. In spite of miconazole having powerful broad-ranged anti-fungal activity including A. apis, it demonstrated strong cytotoxicity. Therefore, even if macelignan alone was effective as an antifungal agent to treat A. apis, combined treatment with miconazole was more useful to overcome toxicity, drug resistance occurrence and cost effectiveness. Finally, HOG1 was revealed as a target molecule of macelignan in the anti-A. apis activity by inhibiting phosphorylation using S. cerevisiae as a model system. Based on our results, macelignan, a food-grade antimicrobial compound, would be an effective antifungal agent against A. apis infection in bees.

Sitios de cría de Aedes aegypti (Linnaeus) y distribución geográfica de Aedes albopictus (Skuse) en la provincia de Limón, Costa Rica. 2012 / Breeding sites of Aedes aegypti (Linnaeus) and geographic distribution of Aedes albopictus (Skuse) in the province of Limón, Costa Rica. 2012

Introducción: en Costa Rica el dengue constituye la principal enfermedad de transmisión vectorial. Su control requiere un conocimiento integral de su principal vector Aedes aegypti, el cual utiliza gran variedad de recipientes artificiales para su cría. Aedes albopictus aunque no se ha relacionado con la trasmisión de esta enfermedad en las Américas, es un excelente vector en Asia y se reporta en Costa Rica desde finales de los 90. Objetivos: identificar y describir los principales sitios de cría del Ae. aegypti y la distribución geográfica de éste y del Ae. albopictus en la provincia de Limón en el año 2012. Métodos: todas las localidades de la provincia fueron muestreadas y visitadas en su totalidad al menos una vez cada cuatro meses por parte del personal de manejo integrado de vectores. En todas las visitas se buscaron todos los recipientes con agua, con presencia o no de larvas de Ae. aegypti y Ae. albopictus. Se tomaron muestras por cada tipo de recipiente donde se encontraron larvas. Resultados: se identificó la presencia de Ae. aegypti en los seis cantones de la provincia de Limón. Los sitios de cría más frecuentes fueron las llantas, los tanques y los baldes. Así mismo se identificó la presencia del Ae. albopictus en cinco de los seis cantones de la provincia. Conclusiones: en la provincia de Limón se encuentran año tras año los mismos sitios de cría del Ae. aegypti tanto en cantidad como en calidad. Así mismo se observa que la proliferación del Ae. aegypti está directamente relacionada con el ser humano, sus malos hábitos, y por la baja calidad de los servicios de salud de protección y mejoramiento del ambiente humano. Estos resultados demuestran que el abordaje del control del Ae. aegypti debe ser integral. Con el reporte del Ae. albopictus en este trabajo y el reporte en Siquirres en el 2009 se ha identificado a esta especie al menos una vez en todos los cantones de la provincia de Limón.

Introduction: dengue is the main vector-borne disease in Costa Rica. Control of dengue requires comprehensive knowledge about its main vector, Aedes aegypti, which may breed in a great variety of artificial containers. Aedes albopictus, on the other hand, has not been associated with dengue transmission in the Americas, but it is an efficient vector in Asia and its presence in Costa Rica has been reported since the late 1990s. Objectives: identify and describe the main breeding sites of Ae. aegypti and the geographic distribution of Ae. aegypti and Ae. albopictus in the province of Limón in the year 2012. Methods: all localities in the province were sampled and visited in their entirety at least once every four months by personnel from the integrated vector management program. During these visits, all containers with water were searched for the presence of Ae. aegypti and Ae. albopictus larvae. Samples were taken from each type of container where larvae were found. Results: Ae. aegypti was found to be present in the six cantons of the province of Limón. The most common breeding sites were pneumatic tires, water tanks and buckets. Aedes albopictus was found to be present in five of the six cantons. Conclusions: the same number and types of breeding sites of Ae. aegypti are found year after year in the province of Limón. It has also been noticed that proliferation of Ae. aegypti is directly related to human beings, their bad habits, and the poor quality of health services in charge of protecting and improving the human environment. These results show that control of Ae. aegypti should be approached in a comprehensive manner. With this report of Ae. albopictus and the 2009 report about Siquirres, the species has been identified at least once in all cantons of the province of Limón.

No Detection of Severe Fever with Thrombocytopenia Syndrome Virus from Ixodid Ticks Collected in Seoul

Larvae, nymphs, and adult stages of 3 species of ixodid ticks were collected by tick drag methods in Seoul during June-October 2013, and their infection status with severe fever with thrombocytopenia syndrome (SFTS) virus was examined using RT-PCR. During the period, 732 Haemaphysalis longicornis, 62 Haemaphysalis flava, and 2 Ixodes nipponensis specimens were collected. Among the specimens of H. longicornis, the number of female adults, male adults, nymphs, and larvae were 53, 11, 240, and 446, respectively. Ticks were grouped into 63 pools according to the collection site, species, and developmental stage, and assayed for SFTS virus. None of the pools of ticks were found to be positive for SFTS virus gene.

Perreyia flavipes larvae toxicity / Toxicidade das larvas de Perreyia flavipes

Fresh or thawed Perreyia flavipes larvae were ground and mixed with water and orally ad ministered to sheep. At 5mg/kg, neither clinical nor enzymatic changes were observed. Unique do ses of 7.5 and 10mg/kg induced characteristic clinical signs of Perreyia sp. larvae poisoning, increased GGT and AST values, and decreased glycemic curves. However, doses of 5, 10, and 15mg/kg repeated at 30 or 15 days intervals caused no disease and mild disease followed by death, respectively. These fin dings indicate that these animals probably developed some degree of tolerance to the toxins in P. flavipes larvae. Ultrastru ctural examination of liver revealed proliferation of the smooth endoplasmic reticulum in the hepatocytes, which may be associated with an increased ability to metabolize toxins and could consequently lead to the tolerance observed in the present study. Further investigations may elucidate whether such tolerance effects could be applied as a control measure for P. flavipes poioning or other hepatotoxic diseases. In addition, clinicopathological findings were discussed.

Larvas frescas ou descongeladas de Perreyia flavipes foram moídas e misturadas com água e administradas de forma oral a ovinos. Com 5mg/kg, não foram observados achados clínicos ou enzimáticos. Doses únicas de 7,5 e 10mg/kg induziram a sinais clínicos característicos de intoxicação pelas larvas de Perreyia sp., os níveis de GGT e AST estavam aumentados e as curvas glicêmicas estavam diminuídas. Entretanto, doses de 5, 10 e 15mg/kg repetidas em intervalos de 30 ou 15 dias não causou doença ou causou doença discreta seguida de morte, respectivamente. Estes achados indicam que estes animais provavelmente desenvolveram algum grau de tolerância para as toxinas presentes nas lar-Larvas frescas ou descongeladas de Perreyia flavipes foram vas de P. flavipes. O exame ultraestrutural do fígado revelou moídas e misturadas com água e administradas de forma proliferação do retículo endoplasmático liso de hepatócioral a ovinos. Com 5mg/kg, não foram observados acha-tos, o que pode ser associado a um aumento na capacidade dos clínicos ou enzimáticos. Doses únicas de 7,5 e 10mg/ de metabolizar toxinas e conseqüentemente levar à tolekg induziram a sinais clínicos característicos de intoxicação rância observada no presente estudo. Outras investigações pelas larvas de Perreyia sp., os níveis de GGT e AST estavam poderão esclarecer se os efeitos de tal tolerância poderiam aumentados e as curvas glicêmicas estavam diminuídas. ser aplicados como medida de controle da intoxicação por Entretanto, doses de 5, 10 e 15mg/kg repetidas em interva-P. flavipes ou outras doenças hepatotóxicas. Além disso, os los de 30 ou 15 dias não causou doença ou causou doença resultados clínico-patológicos foram discutidos.

Ophthalmomyiasis Caused by a Phormia sp. (Diptera: Calliphoridae) Larva in an Enucleated Patient

Ophthalmomyiasis rarely occurs worldwide, and has not been reported in Korea. We present here a case of ophthalmomyiasis caused by Phormia sp. fly larva in an enucleated eye of a patient. In June 2010, a 50-year-old man was admitted to Dankook University Hospital for surgical excision of a malignant melanoma located in the right auricular area. He had a clinical history of enucleation of his right eye due to squamous cell carcinoma 5 years ago. During hospitalization, foreign body sensation developed in his right eye, and close examination revealed a fly larva inside the eye, which was evacuated. The larva was proved to be Phormia sp. based on the morphology of the posterior spiracle. Subsequently, no larva was found, and the postoperative course was uneventful without any complaints of further myiasis. This is the first case of ophthalmomyiasis among the literature in Korea, and also the first myiasis case caused by Phormia sp. in Korea.

Miíase de língua: relato de um caso de infestação hospitalar / Myasis of the tongue: report of a case of hospital infestati

Neste trabalho, relata-se um caso de miíase oral onde será discutida a importância da identificação entomológica e a necessidade de rigorosa vigilância sanitária nos hospitais. Semelhantemente a outros tipos de infestações em áreas endêmicas, as condições epidemiológicas descritas podem indicar que a real prevalência de miíase humana em hospitais pode ser mais alta do que tem sido publicada.

This paper describes a case of oral myiasis and discusses the importance of entomological identification, as well as the need for strict health surveillance in hospitals. Similarly to other types of infestations in endemic areas, the epidemiological conditions described here suggest that the actual prevalence of human myiasis in hospitals may be higher than what has been published.

Cutaneous human myiasis due to Dermatobia hominis / La miasis cutánea humana debido a Dermatobia Hominis

This is a case report of cutaneous myiasis due to Dermatobia hominis in a female physician who had travelled to Belize. Cutaneous myiasis is endemic in Central and South America but is seldom reported from the Caribbean islands.

Éste es un reporte de caso de miasis cutánea debido a Dermatobia hominis en una mujer médico que había viajado a la Belice. La miasis cutánea es endémica en América Central y América del Sur, pero rara vez se reporta en las islas del Caribe.

The exsheathment of Necator americanus infective larvae.

Infective 3rd-stage larvae of Necator americanus were treated with human sweat under various conditions, and compared with human serum, 1.5% saline solution, and distilled water. The infective larvae were observed under inverted microscopy. The highest percentage (14.0%) of the exsheathed larvae was found in human sweat after 2 hours' incubation at 37 degrees C. The proportion of exsheathed larvae in human sweat was significantly different from human serum (p<0.001), 1.5% saline solution (p<0.001), and distilled water (p<0.001). This may reflect the effect of human sweat on the process of skin penetration by Necator americanus larvae.

First report of ophthalmomyaisis externa in Pakistan

Two individuals presented to the Aga Khan University Opthalmology service with foreign-body sensation, pain and redness in one of their eyes. Slit-lamp biomicroscopy revealed tiny larvae crawling around the conjunctival sac. They were mechanically removed under topical anaesthesia and preserved for light microscopy and photography. Comprehensive liaison was established with the Australian Centre for International Agriculture Research for identification of these larvae. Their morphology characterized them as members of fruit-fly, Oestridae family. At least one of them was positively identified as first instar larva of Oestrus ovis. This report describes the first instance of such infections in Southern Pakistan, as concluded after a Medline search

Evaluación de la técnica inmunoensayo en capa delgada utilizando microplacas, en la detección de anticuerpos cirulantes de Oestrus ovis, en ovinos infestados naturalmente / Evaluation of the immunoassay test in thin layer, using microplates of polyestirene for the detection of circulating antibodies of Oestrus ovis naturally infected ovines

Introducción. La estrosis es una miasis cavitaria que afecta a los ovinos y caprinos. En la actualidad el diagnóstico es a través de la observación de los signos clínicos y el hallazgo de larvas en los conductos nasales de los animales a la necropsia. Diferentes técnicas serológicas se han utilizado y evaluado para tratar de realizar un mejor diagnóstico de esta enfermedad. Objetivo. Evaluar la prueba de inmunoensayo en capa delgada (ICD) utilizando microplacas de poliestireno, para el diagnóstico de estrosis ovina. Material y métodos. Se utilizaron 95 ovinos sacrificados para abasto, de los cuales se obtuvo el suero y se les realizó el examen postmorten para la detección de la presencia de larvas en los conductos nasales. La presencia de larvas en los conductos nasales fue considerada como prueba de oro. El antígeno usado fue a partir de larvas L2 con una concentración de proteína de 4.2 mg/mL. La prueba se realizó en microplacas de poliestireno de fondo plano y de 96 pozos, se siguió el mismo procedimiento utilizado en la técnica descrita por Bautista 1982. Se determinó la sensibilidad y se midió la concordancia entre ambas pruebas, calculando el valor de kappa. Resultados. De los 95 ovinos sacrificados, 51 (54 por ceinto) fueron positivos, a la preencia de larvas en el examen postmortem y 61 (51 por ciento) a la prueba de ICD y u valor de kappa de 0.53 al comparar ambas pruebas. Conclusiones. El uso de microplacas en la prueba ICD es una alternativa para el diagnóstico de estrosis ovina en estudio epidemiológicos ya que permite con una sensibilidad alta, analizar una mayor cantidad de sueros por placa, utilizando una menor cantidad de antígeno

Ocorrencia do berne, dermatobia hominis diptera cuterebridae em varios hospedeiros, no Rio de Janeiro, Brasil / Occurrence of berne, dermatobia hominis diptera cuterebridae in several host, in Rio de Janeiro, Brazil

Relata-se casos de hospedeiros apresentando infestacao com larvas de D. hominis no Rio de Janeiro, Brasil. Foram observadas larvas do berne em suíno, caprino, felino, canino e homem. Esse relato tem importancia pelo fato inédito de localizacao da larva na orelha de um suino e no prepúcio de um cao, e esses nao serem hospedeiros comuns das larvas do berne. As observacoes foram feitas em áreas com grandes incidencia do berne em bovinos. No trabalho fazse uma revisao da ocorrencia da dermatobiose nessas espécies

Resistência de Biomphalaria glabrata à infecção pelo Schistosoma mansoni: variaçoes no período pré-patente e na compatibilidade / The resistance of Biomphalaria glabrata to Schistosoma mansoni infection: variations in the prepatent period and in compatibility

Biomphalaria glabrata de Belo Horizonte, Minas Gerais, Brasil, criada no laboratório, apresenta 90% de taxa de infecção com 20 miracídios da cepa LE, autóctone. O período pré-patente normal varia de 5 a 7 semanas enquanto 5 a 10% dos moluscos expostos não eliminam cercárias. Os descendentes de exemplares negativos foram novamente submetidos à infecção individual com 20 miracídios. A média de infecção da F14 a F20 foi de 43,6%. Cortes histológicos de moluscos da F12, F14 e F15 mostraram reações teciduais nos exemplares eliminando menos de 10 cercárias. Um período pré-patente prolongado, 17 a 32 semanas, foi observado em 35 (17,9%) dos 195 exemplares infectados. Os índices de cercárias da F12, F13 e F15 baixaram de extremamente compatíveis (classe VI) para muito compatíveis e compatíveis (classes V e III) mostrando a compatibilidade menor dos moluscos selecionados.

Biomphalaria glabrata from Belo Horizonte, Minas Gerais, Brazil, reared in laboratory, has a level of infection of 90% when exposed to 20 miracidia of the autochibonous LE strain. The prepatent period was of 5 to 7 weeks whereas 5 to 10% of exposed snails do not shed cercariae. The eggs of negative snails were collected and the progeny was again submitted to individual infection with 20 miracidia. The mean of infection from F14 to F20 was of 43.6%. Histological sections from F12, F14 and F15 snails showed tissue reactions in those specimens shedding less than 10 cercariae. A prepatent period of 17 to 32 weeks was observed in 35 (17.9%) of 195 infected snails. The index of cercariae of control was extremely compatible and for F12, F13 and F15 snails varied from very compatible class V to compatible class III, showing less compatibility in selected snails.

Oestrus ovis [sheep nasal fly] infesting the eyes and the nose of a camel keeper family

Myiasis is a medical and veterinary health problem in many animal rearing countries. It is not a new problem in Egypt. A family of 5 persons was infested in the eyes [5] and nose [2] with the larvae of Oestrus ovis. It was concluded that the physicians in the MOH rural health units should keep in mind ophthalmomyiasis when dealing with non-specific catarrhal conjunctivitis, particularly those people who are concerned with rearing of farm animals

Angiostrongilose abdominal: profilaxia pela destruiçäo das larvas infectantes em alimentos tratados com sal, vinagre ou hipoclorito de sódio / Abdominal angiostrongylosis: prophilaxis through treatment of food with solutions of saturated sodium chloride, vinegar and sodium hypochlorite

There is a high prevalence of accidental human infection with Angiostrongylus costaricensis in some areas in southern Brazil and sometimes it presents as severe intestinal disease. Prophylaxis is important since there is no medical treatment for the disease. The ingestion of fruits and vegetables contaminated with the mucous secretion of infected molluscs (the intermediate hosts) is one of the proposed modes of transmission. Third stage larvae were incubated at 5 degrees C for 12 hours, in solutions of saturated sodium chloride, vinegar and sodium hypochlorite 1.5 per cent. The larvae had their viability tested through inoculation into albino mice. The percentage of larvae that established infection were 0 per cent in the group treated with sodium hypochloride, 1.8 per cent with NaCl and 2.4 per cent with vinegar. In conclusion, all substances tested reduced the population of viable larvae and may be useful in food decontamination, as a prophylactic measure for abdominal angiostrongylosis.

In vitro transmission of Wuchereria bancrofti L3-stage larvae by experimentally infected culex pipiens L [Diptera: culicidae]

Females of Culex pipiens L. experimentally infected with Wuchereria bancrofti were tested for in vitro transmission of infective stage L[3] larvae using a capillary tube technique. Of the females harbouring L[3] larvae, 60.7% [34/56] transmitted a geometric mean of 2.84 L[3] larvae [range 1- 35]. Transmitting Cx. pipiens contained significantly more L[3] larvae than non-transmitters. Both the probability of transmission and the number of L[3] larvae transmitted were related to the total number of L[3] larvae/mosquito. Almost all females with L[3] loads >/= 10 transmitted larvae in vitro. The possibility is discussed that the detection of L[3] larvae in field collected mosquitoes by dissection may overestimate the proportion capable of parasite transmission and the proportion of L[3] larvae deposited on host skin by Ca. 40%

"Larva currens": relato de dois casos / \"Larva currens\": two case report

O autor relata dois casos de erupçäo cutânea, extremamente pruriginosa, com eosinofilia importante e concomitante com infestaçäo por S.stercoralis (Larva currens).

Movement of stomach bots [gasterophilus intestinalis and gasterophilus pecorum larvae] in the oral cavity of donkeys [equus asinus]

Examinations were carried out on oral cavities of 56 and 15 donkeys naturally infested with Gasterophilus intestinalis and G. pecorum, respectively. Developing immature larvae of these two species showed a specific pattern of movement within the oral cavity of donkeys. First instars of G. intestinalis burrowed in the dorsal mucosa of the tongue and invaded the interdental spaces of the upper arcade teeth. Second instar larvae also developed there and in the pharynx. First instars of G. pecorum burrowed in the mucous membrane of the hard palate, cheeks and tongue. They dispersed into the soft palate and root of the tongue, where 2nd instars developed. Second instars moved to the pharynx, where they remained until the moult to 3rd instar. Like G. intestinalis, the dispersing 1st instar produced perpendicular air holes for breathing

Biological and morphological characteristics of Schistosoma mansoni from Ribeira Valley, state of Säo Paulo, Brazil I--Susceptibility of Biomphalaria tenagophila snail to sympatric S. mansoni strain

In the Säo Paulo State, Brazil, where the Biomphalaria tenagophila is the intermediate host, the Ribeira Valley is an important endemic schistosomiasis mansoni area. During last eleven years there has been intense control measures focusing on schistosomiasis. The efforts have been concentrated in the municipalities of Pedro de Toledo and Itariri. We determined the susceptibility of B. tenagophila to sympatric strain of S. mansoni, both recently isolated from Itariri field. In 1988, this strain was isolated and maintained in the experimental model: Swiss mice--sympatric B. tenagophila. The second generation of the worm was evaluated. The snail were divided in the three groups of 60 snails each. One group was exposed to 1 miracidium and other to 10. The third group was the control. The mortality and the shedding of cercariae were checked during 78 days. After that, the positive snails were observed until they ceased to shed cercariae. The exposed molluscs showed mortality rates of 23% and 31% and infection indexes were of 8% and 60% to 1 and 10 miracidia respectively. The mortality was of 22% in the control group. The periods of shedding cercariae in the two groups were 82 and 104 days. We can conclude that B. tenagophila is an effective intermediate host to the sympatric strain of S. mansoni sympatric strain